<!DOCTYPE html>
<html>
<body>
  <canvas id="canvas" width="500", height="500"> </canvas>
  <script>
  var canvas = document.getElementById("canvas");
  var width = canvas.width;
  var height = canvas.height;
  var ctx = canvas.getContext("2d");
  for (var i = 0; i < width; i += 10) {
    ctx.moveTo(i, 0);
    ctx.lineTo(i, height);
    ctx.stroke();
  }
  </script>
</body>
</html>
